Authors:
Andrew J. Lee
Judith M. Dawes
Michael J. Withford
Centre of Ultrahigh-bandwidth Devices for Optical Systems (CUDOS) and MQPhotonics Research Centre, Department of Physics, Macquarie University, 2109 NSW, Australia

We present a novel method for profiling high aspect ratio and undercut laser drilled holes using sacrificial layers. This profiling method is used to compare and contrast laser ablation of polyethylene films under exposure to ultraviolet (266 nm) and near-infrared (800 nm) radiation from an ultrafast, femtosecond laser. We find that ultraviolet femtosecond pulsed laser processing of this polymer exhibits similar characteristics to that reported for nanosecond pulsed excimer lasers; namely, that thermal ablation contributes to material removal at high fluences. In addition, the total volume of material removed via IR femtosecond laser ablation is shown to be up to 4 times that for UV femtosecond laser ablation at a similar fluence and low pulse repetition frequency.